What is layering in computer networks?

When two remote computers communicate, multiple different tasks like digitization, packetization, transmission, routing etc are needed. Layering is nothing but splitting these different kinds of tasks needed into different distinct logical functions or layers. It is analogous to a divide and conquer strategy, where a bigger problem is split into smaller sub-problems so as to solve it easily.

A sample diagram of the 7 layer OSI model is given below:

7 Layer OSI Model

In layering, the set of tasks required for computer communication are split into different distinct functions (layers).

All the layers combine together to achieve the desired computer communication functionality.

It provides modularity to the whole architecture

Also, there is a hierarchy among layers, as each layer provides a set of specific functions to the layer above it

Inter layer communication is through well defined interfaces named as Service Access Points(SAPs).

Some examples of layering are the OSI 7 layer model, the TCP/IP 4 layer model and the practically used Hybrid 5 layer model.